Objective: To elucidate the characterization of rpoB mutation in rifampin - resistant clinical isolates of Mycobacterium tuberculosis isolates from China.
Methods: 588 bp DNA fragment of rpoB gene including 81 bp code region (rifampin resistance determination region, RRDR) was sequenced. 242 strains of Mycobacterium tuberculosis, including 193 rifampin - resistant strains and 46 rifampin - susceptible strains and 3 artificially induced rifampin - resistant strains were sequenced.
Results: 89.1% (172/193) rifampin - resistant strains had rpoB gene mutations in RRDR, no mutation was found in rifampin - susceptible strains. 46.1% rifampin - resistant strains had mutations located at 531-Ser; 17.1% strains had mutations located at 526-His; Combinative mutation rate was 12.4%; 4 strains had synonymous mutations; No deletion or insertion mutation was found among all strains. High level rifampin resistant strains (250 microgram/ml rifampin resistant) had higher mutation frequency at 531 - Ser than low level rifampin resistant strains (50 microgram/ml rifampin resistant) (P < 0.05).
Conclusions: About 90% rifampin resistant clinical strains of Mycobacterium tuberculosis from China had rpoB mutations; 531-Ser and 526 - His were the most common positions to be substituted, the added mutation rate was about 46%; High level rifampin resistant strains had a higher frequency of 531-Ser mutation than low level rifampin resistant strains; No insertion or deletion mutation was found in these specimens; DNA sequencing is significant in drug choosing for tuberculosis treatment.